Rotary crusher hammers

ABSTRACT

In a rotary hammer crusher, at least two hammers are employed at each hammer position, each hammer being independently pivotally suspended from the rotor disc. The front hammer (as determined by the direction of rotation of the rotor shaft) functions as the wear hammer and is made of manganese or other steel having good wear-resistant properties. This hammer is usually light in weight and thin in thickness compared with the rear or backup hammer. The front hammer is so shaped and so pivotally suspended relative to the backup hammer than when the rotary crusher is rotating at operating speed, the front hammer maintains an abutting relationship against the heavy mass backup hammer, and the two hammers function as a single unit. If the rotary crusher is a reversible crusher, three hammers are usually used at each position, the middle hammer being the backup hammer.

United States Patent (72} Inventor William F. Hahn Devon, Pa. 211 App! No 811,541 [22] Filed Mar. 28, 1969 (45) Patented July 20,1971 [73] Assignce Pennsylvania Crusher Corporation Broomall, Pa.

[54] ROTARY CRUSHER HAMMERS 11 Claims, 3 Drawing Figs.

[52] U.S. Cl 241/194, 241/195, 241/300 [51] lnt.Cl .B02c 13/04, B02c 13/28 [50] Field of Search 241/194, 197, 300, 195

[56] References Cited UNITED STATES PATENTS 1,947,784 2/1934 Armstrong 241/194 2,822,138 2/1958 Olive...

Primary Examiner- Robert C Riordon Assistant ExaminerGary L Smith Atlorney-Paul & Paul ABSTRACT: In a rotary hammer crusher, at least twohammers are employed at each hammer position, each hammer being independently pivotally suspended from the rotor disc. The front hammer (as determined by the direction of rotation of the rotor shaft) functions as the wear hammer and is made of manganese or other steel having good wear-resistant properties. This hammer is usually light in weight and thin in thickness compared with the rear or backup hammer. The front hammer is so shaped and so pivotally suspended relative to the backup hammer than when the rotary crusher is rotating at operating speed, the front hammer maintains an abutting relationship against the heavy mass backup hammer, and the two hammers function as a single unit. If the rotary crusher is a reversible crusher, three hammers are usually used at each position, the middle hammer being the backup hammer.

PATENTED JULZO I971 flg J INVENTOR. William F. Hahn ATTORNEYS.

ROTARY CRUSHER HAMMIEIRS BACKGROUND OF THE INVENTION In rotary hammer crushers and pulverizers for fragmenting and reducing the size of coal, stone, and other material, much thought has been given to ways and means for increasing the wear life of the hammers. The hammers are, of course, subjected to large wear and impact forces, and the replacement of worn hammers has been an expensive and troublesome problem, particularly in view of the increasingly large sizes and weights of the hammers of a modern day rotary crushing machine. The single hammer may, for example, weigh as much as 1,400 pounds, and even larger hammers are contemplated.

SUMMARY OF THE INVENTION The object of the present invention is to provide means for reducing the cost involved in replacing worn hammers in a rotary crusher. Heretofore, a single hammer has been provided at each hammer position. According to the present invention, at least two hammers are provided at each hammer position. (In a reversible rotary crusher, two or more hammers, preferably three, are provided at each position.) The front hammer (as deten'nined by the direction of rotation of the rotary crusher) is usually a relatively lightweight hammer of manganese or other material having good wear-resistant properties. The rear hammer is usually a heavy large mass hammer of carbon or other less expensive steel, and functions as a backup hammer. Both hammers are so pivotally supported from the rotor disc that when the crusher is rotating at operating speed, and the hammers have assumed their radially extended positions (which they assume due to the centrifugal forces involved) the rearward face of the front hammer is maintained in abutting relation with the front face of the heavy backup hammer, due to component forces produced as a result of the pivot points and center of gravity considerations, with the result that the abutting hammers function as a single hammer with no relative chattering and knocking of one hammer against the other during operation. When the front hammer wears down to an extent that calls for replacement, it is replaced many times, without need for replacing the main mass or backup hammer.

In the case of a reversible rotary crusher, two or more hammers, generally three, are provided at each hammer position, the middle hammer being the heavy mass backup hammer and the exterior hammers usually being the lightweight wear hammers. Both of the wear hammers are so shaped and so pivotally supported on the rotor disc that when the hammers have assumed their radially extended positions as determined by centrifugal forces, both wear hammers are maintained in abutting engagement with the middle backup hammer irrespective of the direction of rotation of the rotor shaft.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front elevational diagrammatic view of a rotary crusher showing three hammers at each hammer position, in accordance with the present invention;

FIG. 2 is an enlarged diagrammatic view showing the three hammers at a single hammer position, and showing the rela' tionship between the hammer pivot points and the centers of gravity or the center of mass of the wear hammers;

FIG. 3 is a fragmentary view of a modified form of hammer system in which the main mass which serves as the backup hammer is fixed to the rotor disc as an integral or nonintegral part thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, no effort has been made to show the details of construction of the rotary crusher since the present invention concerns only the hammers. It will be sufficient to say that the rotary crusher may be of any well-known type. In its operation, coal, stone, or other material to be fragmented is fed to the crusher through the feed hopper 10 and is struck by the hammers identified comprehensively by the reference numeral 20. In FIG. I, the rotary crusher is illustrated as rotating in the clockwise direction. The hammers are pivotally suspended from and are carried rotationally by discs 31 which are mounted for rotation on and driven by rotor shaft 32. The coal or other material, after being struck and fragmented by a hammer, is thrown against a surface which in the illustrated embodiment is the face 12 of one of the breaker blocks shown where the particles are further fragmented and reduced in size. This action is repeated as the material makes it way down through the crusher and is finally delivered through the discharge opening or exit 14.

The hammers, identified generally as 20, are pivotally suspended from the discs 31 at a plurality of spaced-apart hammer positions. In the drawing, six such hammer positions are shown, at 60 spacings. The machine may, of course, have a different number of hammer positions and many rows of hammers.

According to the present invention if the rotary crusher is a reversible crusher, two hammers or more, generally three, are provided at each hammer position. If the crusher is not reversible, two hammers are generally provided at each hammer position. In the drawing, the crusher is assumed to be reversible and three hammers are illustrated. at each position.

In the three-hammer-per-position arrangement illustrated in the drawing, the second or center hammer 22 and also the third hammer 23 function as the backup mass. Hammer 22 is usually larger and heavier relative to the hammers 21 and 23 located on either side thereof. It is proposed that the center heavy mass hammer 22 may be made of less expensive material, such as carbon steel. The first and third hammers 21 and 23, which function as the wear hammers, are usually smaller and lighter in weight than the second or backup hammer. The wear hammers are made of relatively expensive material, such as manganese steel, having good wear resistance to abrasive or high impact forces.

Each of the three hammers in the group is pivotally sup ported on the rotor disc 31 at closely related pivot points. The present invention contemplates that, when the crusher is rotating at operating speed, the wear hammers 21 and 23 willv be held in close abutting relation against the heavy backup hammer 22 irrespective of the direction of rotation of the crusher, and that there will be no chattering between the wear hammers and the backup hammer 22. To accomplish this desirable result, the wear hammers 21 and 22 are pivotally mounted at pivot points 4] and 43, respectively, which are not outside the angle A defined by theradial lines 51 and 53 which extend from the center axis of rotation of the crusher to the centers of mass or centers of gravity 61 and 63 of the wear hammers 21 and 23 after the hammers have been worn down to the limits preselected as the wear limit. So longas the pivot points 41 and 43 are not outside the angle A the wear hammers 21 and 23 will, during rotation of the rotor shaft at operating speed, move toward the main mass or backup hammer 22 and will be held tightly against the backup hammer.

IN FIG. 2, the portions of hammers 21 and 23 which are subject to being worn away are depicted by the dashed lines, and the centers of mass or centers of gravity of the hammers 21 and 23, in new unworn condition, are represented by the dots 161 and 163, respectively. An angle A depicts the angle between radial lines extending from the center axis of rotation C of the rotor shaft 32 to the centers of gravity 161 and 163 of the unworn hammers 21 and 23. The pivot points 41 and 43 from which the hammers 21 and 23 are suspended are seen to be well within the angle A. In FIG. 2, the hammers 21 and 23 are represented as wearing down to a flat face indicated by the solid line, but at least in many cases the worn down face will be rounded or arcuate rather than flat.

It will be understood, of course, that when the crusher is rotating clockwise, the hammer 21 is the front hammer (the term front" being relative according to the direction of rotation) and that it is hammer 21 which strikes the material to be crushed. In this direction of rotation of the crusher, the rearmost'hammer 23 is for the most part functionally idle. it does, to some extent, function as a backup hammer, but it is not necessary for this purpose, so that if the crusher is to be a nonreversible crusher, the third hammer is omitted.

Returning now to the description of the crusher shown in the drawing, and assuming it to be rotating clockwise as in dicatedby the arrow, as the front surface of the hammer 21 gradually wears away, the center of mass or center of gravity 161 of the hammer moves rearwardly, i.e. toward the main mass or backup hammer 22. So long as the pivot point of the wear hammer is not outside the angle A, or, in terms of oneway rotation, so long as the pivot point 41 of hammer 21 is not outside the angle B defined by a radial line through the shifting center of mass of the hammer 21 and a radial line through the pivot point 42 of the main mass hammer 22, the hammer 21 will, during operation at rated speed, be maintained in abutment against the backup hammer 22.

When the rotary crusher is rotating clockwise, as just described, the rearmost hammer 23 is functionally idle, at least so far as striking the coal or other material is concerned, but so long as its pivot point 43 is not outside the angle A defined by radial lines through the centers of mass of the wear hammers 21, 23 and in particular, so long as the pivot'point 43 is not outside the angle C one side of which is defined by a radial line through the shifting center of mass of the hammer 23, the hammer 23 will be urged toward the main mass hammer 22 and will maintain abutting contact therewith.

Particular shapes for the wear and backup hammers have been shown diagrammatically in the drawing. The invention is not, however, limited to these shapes nor to a fixed number of pin connections in relation to the number of hammers per group. As previously indicated, the important aspects of the invention are that there be at least two hammers at each position, one, a wear hammer and the other a backup hammer and that these hammers be so shaped and so pivotally mounted that the pivot point of the wear hammer is at least as close to the pivot point of the backup hammer as a radial line which extends from the center axis of rotation of the crusher to the center of gravity of the wear hammer when worn out or at its limit condition of wear.

In some instances, it may be desirable to design the hammer system to hang-the wear hammer (or wear hammers) on the same pivot pin which supports the backup hammer. in other words, the wear and backup hammers may be so designed that all hammers (at a hammer position) hang on a single pin through the discs. in such case, the center of mass of the wear hammer would always be outside of the pivot point of the wear hammer in relation to a radial line drawn from the center of the rotor shaft through the center of mass of the wear hammer, and the wear hammers would always rest tightly against the center or backup hammer.

in some cases, it may be desirable to design the hammer system to have one pivot point on the disc for the main mass hammer, with one or more pivot points for the wear hammers on the shank of the main mass hammer, probably outwardly from the disc. In other words, the main mass hammer would be pivotally connected to the disc, and would have an additional pivot point on its shank, perhaps outwardly from the disc, to which the wear hammers would be pivotally attached.

The present invention also contemplates that the number of pivot points need not be equal to, nor even correlated to, the number of hammers. For example, the center or backup hammer may, in some cases, be nonpivotally mounted, i.e. may be fixed rigidly or nonrigidly to the disc, as is illustrated in FIG. 3, wherein the center or main mass hammer 122 is shown fixed to disc 131 and wear hammers 121 and 123 are pivotally supported thereon.

What 1 claim is:

1. in a rotary hammer crusher:

a. a rotary shaft,

b. hammer support means onsaid shaft supporting hammers at a plurality of circumferentially spaced hammer positions,

c. each hammer position having at least two hammers, a

from wear hammer facing in the direction of rotation of said rotor shaft for striking the material to be crushed and a rear backup hammer for backing up said front hammer, said front wear hammer and said rear backup hammer being supported on said hammer support means at related locations, said front wear hammers being pivotally supported at a pivot point not outside an angle defined by a radial line extending from the center axis of rotation of the rotor shaft through the center of mass of said wear hammer and a radial line extending through the center of mass of said backup hammer, said front wear being so shaped and so pivotally supported relative to said backup hammer that, when said rotor shaft is rotating at operating speed and said front wear hammer is extended radially outward to its operating position as determined by centrifugal forces, the rearward face of the front wear hammer maintains abutting engagement against the forward face of the backup hammer, whereby said hammers function as a single hammer unit.

2. Apparatus according to claim 1 characterized in that said front hammer is made of material having substantially higher wear-resistant properties than said backup hammer, and is substantially lighter in weight than said backup hammer.

3. Apparatus according to claim 1 characterized in that said front wear hammer is supported at a pivot point on said hammer support means rearward of a radial line which extends from the center axis of rotation through the center of mass of the wear hammer in unworn condition.

4. Apparatus according to claim 2 characterized in that said front wear hammer is supported at a pivot point on said hammer support means rearward of a radial line which extends from the center axis of rotation through the center of mass of the wear hammer in unworn condition.

5. Apparatus according to claim 1 characterized in that the rotary hammer crusher is reversible, and in that three hammers are provided at each hammer position, the outer two being wear hammers, the center one being the backup hammer, the wear hammers being pivotally supported at pivot points located within the angle defined by radial lines which extend from the center axis of rotation and pass through the centers of mass of the wear hammers when worn to their preselected limits of wear.

6. Apparatus according to claim 1 characterized in that said backup hammer is fixed nonpivotally to said hammer support means.

7. In a rotary hammer crusher:

a. a rotary shaft,

b. hammer support means on said shaft pivotally supporting hammers at a plurality of circumferentially spaced hammer positions,

0. each hammer position having at least two hammers, a front wear hammer facing in the direction of rotation of said rotor shaft for striking the material to be crushed and a rear backup hammer for backing up said front hammer,

d. said front wear hammer and said rear backup hammer being pivotally supported on said hammer support means at related locations,

e. said front wear hammer being pivotally supported at a pivot point on said hammer support not outside an angle defined by a radial line extending from the center axis of rotation of the rotor shaft through the center of mass of said wear hammer and a radial line extending through the pivot point of said backup hammer, said front wear and rear backup hammers being so shaped and so separately pivotally supported that, when said rotor shaft is rotating at operating speed and said hammers are extended radially outward to their operating positions as determined by centrifugal forces, the rearwardface of the front wear hammer maintains abutting engagement: against the forward face of the backup hammer; whereby said hammers function as a single hammer unit.

8. Apparatus according to claim 7 characterized in that said front hammer is made of material having substantially higher wear resistant properties than said backup hammer, and is substantially lighter in weight than said backup hammer.

9. Apparatus according to claim 7 characterized in that said front wear hammer is supported at a pivot point on said hammer support means rearward of a radial line which extends from the center axis of rotation through the center of mass of the wear hammer in unworn condition.

l0. Apparatus according to claim 8 characterized in that said front wear hammer is supported at a pivot point on said hammer support means rearward of a radial line which extends from the center axis of rotation through the center of mass of the wear hammer in unworn condition.

11. Apparatus according to claim characterized in that the rotary hammer crusher is reversible, and in that three hammers are provided at each hammer position, the outer two being wear hammers, the center one being the backup hammer, the wear hammers being pivotally supported at pivot points located within an angle defined by radial lines which extend from the center axis of rotation and pass through the centers of mass of the wear hammers when worn to preselected limits of wear. 

1. In a rotary hammer crusher: a. a rotary shaft, b. hammer support means on said shaft supporting hammers at a plurality of circumferentially spaced hammer positions, c. each hammer position having at least two hammers, a front wear hammer facing in the direction of rotation of said rotor shaft for striking the material to be crushed and a rear backup hammer for backing up said front hammer, d. said front wear hammer and said rear backup hammer being supported on said hammer support means at related locations, e. said front wear hammers being pivotally supported at a pivot point not outside an angle defined by a radial line extending from the center axis of rotation of the rotor shaft through the center of mass of said wear hammer and a radial line extending through the center of mass of said backup hammer, f. said front wear being so shaped and so pivotally supported relative to said backup hammer that, when said rotor shaft is rotating at operating speed and said front wear hammer is extended radially outward to its operating position as determined by centrifugal forces, the rearward face of the front wear hammer maintains abutting engagement against the forward face of the backup hammer, whereby said hammers function as a single hammer unit.
 2. Apparatus according to claim 1 characterized in that said front hammer is made of material having substantially higher wear-resistant properties than said backup hammer, and is substantially lighter in weight than said backup hammer.
 3. Apparatus according to claim 1 characterized in that said front wear hammer is supported at a pivot point on said hammer support means rearward of a radial line which extends from the center axis of rotation through the center of mass of the wear hammer in unworn condition.
 4. Apparatus according to claim 2 characterized in that said front wear hammer is supported at a pivot point on said hammer support means rearward of a radial line which extends from the center axis of rotation through the center of mass of the wear hammer in unworn condition.
 5. Apparatus according to claim 1 characterized in that the rotary hammer crusher is reversible, and in that three hammers are provided at each hammer position, the outer two being wear hammers, the center one being the backup hammer, the wear hammers being pivotally supported at pivot points located within the angle defined by radial lines which extend from the center axis of rotation and pass through the centers of mass of the wear hammers when worn to their preselected limits of wear.
 6. Apparatus according to claim 1 characterized in that said backup hammer is fixed nonpivotalLy to said hammer support means.
 7. In a rotary hammer crusher: a. a rotary shaft, b. hammer support means on said shaft pivotally supporting hammers at a plurality of circumferentially spaced hammer positions, c. each hammer position having at least two hammers, a front wear hammer facing in the direction of rotation of said rotor shaft for striking the material to be crushed and a rear backup hammer for backing up said front hammer, d. said front wear hammer and said rear backup hammer being pivotally supported on said hammer support means at related locations, e. said front wear hammer being pivotally supported at a pivot point on said hammer support not outside an angle defined by a radial line extending from the center axis of rotation of the rotor shaft through the center of mass of said wear hammer and a radial line extending through the pivot point of said backup hammer, f. said front wear and rear backup hammers being so shaped and so separately pivotally supported that, when said rotor shaft is rotating at operating speed and said hammers are extended radially outward to their operating positions as determined by centrifugal forces, the rearward face of the front wear hammer maintains abutting engagement against the forward face of the backup hammer, whereby said hammers function as a single hammer unit.
 8. Apparatus according to claim 7 characterized in that said front hammer is made of material having substantially higher wear-resistant properties than said backup hammer, and is substantially lighter in weight than said backup hammer.
 9. Apparatus according to claim 7 characterized in that said front wear hammer is supported at a pivot point on said hammer support means rearward of a radial line which extends from the center axis of rotation through the center of mass of the wear hammer in unworn condition.
 10. Apparatus according to claim 8 characterized in that said front wear hammer is supported at a pivot point on said hammer support means rearward of a radial line which extends from the center axis of rotation through the center of mass of the wear hammer in unworn condition.
 11. Apparatus according to claim 7 characterized in that the rotary hammer crusher is reversible, and in that three hammers are provided at each hammer position, the outer two being wear hammers, the center one being the backup hammer, the wear hammers being pivotally supported at pivot points located within an angle defined by radial lines which extend from the center axis of rotation and pass through the centers of mass of the wear hammers when worn to preselected limits of wear. 